Steam generator



Se t. 22, 1964 a. a AUSAH' sm M mm 58 Lheets-Sheet 1 Filed Aug, 2,, 19.62

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O0OO+OOOO &) 000 0000 o o o o q o INVENTOR. Srevg J. Perslnskle Worme L. Sage George Muse? ATTORNEY Sept. 22, 1964 e. MUSAT ETAL.

STEAM GENERATOR 8 Sheets-Sheet 2 Filed Aug. 2, 1962 Musut INVENZ0R. Steve J. Persmskle Wurnie L. Sage BY ,George ATTORNEY Sept. 22, 1964 e. MUSAT ETAL STEAM GENERATOR 8 Sheets-Sheet 3 Filed Aug. 2, 1962 II FIHI'H'IFIFI STEAM GENERATOR 8 Sheets-Sheet 4 Filed Aug. 2, 1962 FIG. 4

INVENTOR.

Steve J. Persinskle Wurnie L. So a BY George Muse? ATTORNEY P 1964 i G. MusAT ETAL I 3,149,614

STEAM GENERATOR Filed Aug. 2., 1962 8 Sheets-Sheet 5 Stevq J. Perslnskle warms L. Sage BY GeorqrMusot TOBN Y Sept. 22, 1964 e. MUSAT ETAL 3,149,614

' STEAM GENERATOR Filed Aug. 2, 1962 8 Sheets-Sheet 6 INV EN TOR.

Steve J. Persinskie Warnie L. Sage BY George Musa'r ATTORNEY Sept. 22, 1964 s. MUSAT ETAL STEAM GENERATOR 8 Shets-Sheet '7.

FIG.7

STEAM GENERATOR a Sheets-Sheet 8 Filed Aug. 2, 1962 FIG.8.-

INVENTOR. Steve J. Persinskle .Wornie L. So

a BY George Musa ATTORNEY United States Patent H STEAM GENERATGR Eeorge Musat, Canto'n, Steve I. Persin'skie, Barber-ton, and Warnie L. sage, Louisviile, Ohio, assignors to The Bab-cock & Wilcox company, New York, N.Y., a corpartition of New Jersey Filed Aug; 2, 1962, Ser. No. 214,301 8 Claims. ,(Ci. 1222-35) This invention relates in general to the construction and operation of steam generators and more particularly to improvements in the construction and operation of water tube boilers of the shop-assembled type.

The packaged or shop-assembled boiler is greatly in demand by industry because of its lower cost and shorter delivery time as compared to field assembled units. The minimum cross-section of a unit of this type is dictated by shipping clearances. Since the steam generating surface must be increased as the steam generating capacity of the unit is increased, the space available for burning the fuel must of necessity become smaller as capacity increases in order to meet the size limitations for shipping. Thus the capacity of known types of packaged boilers with conventional firing systems is limited by the minimum furnace volume required to burn the required amount of fuel. Thus far the top continuous rating achieved with packaged type boilers within the limitations imposed by shipping clearances has been 120,000 lbs. steam/ hr. A packaged type boiler having furnace, steam generating surface and burner equipment so proportioned and arranged as to efficiently achieve burning of suitable fuel quantities in the minimum furnace volume, while providing a substantial increase in steam generating capacity beyond the present ceiling without exceeding unit size limitations imposed by shipping clearances, is, therefore, highly desirable. Such a unit should also be economical to build, require a minimum of controls, have a wide load range, and use a minimum of fan power.

Thus the general object of the present invention is the provision of a shop-assembled steam generator possessing the virtues of compactness, portability, simplicity, reliability and ability to provide sustained efiicient opera-- tion at steam generating rates far exceeding,- by as much as 25%, those attainable in prior packaged units of corresponding physical size. A further and more specific object of the invention is the provision of a steam generating unit of the type described which is characterized by an arrangement of fuel burning provisions and a furnace construction permitting the burning of liquid and gaseous fuels at rates of heat release per cubic foot of furnace volume markedly beyond those of prior constructions of like character; its readiness upon delivery to be skidded or lifted onto the foundation, hooked up and placed in operation, thereby saving in the cost of building and erection; an arrangement of steam generating surface in the furnace increasing the effectiveness of the furnace without increasing its volume or outside space requirements: and its ability to deliver a uniform steam temperature over a Wide load range and to satisfactorily respond to wide and frequent load swings.

In accordance with the invention the steam generating unit is of the shop-assembled or packaged type and comprises walls including steam generating tubes forming a setting divided by partitions into a pair of convection heating gas passes and a furnace opening at one end to each of the heating gas passes, with the furnace being supplied with heating gases at its opposite end by a cylindrical combustion chamber formed by Walls including steam generatingtubes. Each of the heating gas passes is occupied by a bank of steam generating tubes having their upper ends connected to a steam and water drum extendin longitudinally of and overlying the furnace and comarrests Patented Sept. 22., 1964 bustion chamber and their lower ends connected to a lower water drum extending longitudinally of and underlying the furnace, with provisions for connecting the steam generating tubes of the combustion chamber to the upper and lower drums.- Special provisions are made for supplying liquid and gaseous fuels to the combustion chamher and for supplying additional combustion air to the combustion gases discharging from the combustion chamher into the furnace, to the ends of minimizing combustion chamber gas pressure drop, providing a burner flame shape designed to prevent impingement on combustion and furnace chamber walls, providing complete combustion of the fuel before the gases enter the convection surfaces, and eliminating pulsations in the combustion chamber.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification.- For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated and described.

Of the drawings:

FIG. 1 is a plan section of a steam generator constructed in accordance with the invention taken along the line 1-31 of FIG; 5;

FIG. 2 is a vertical section taken along the line 22 of FIG. 3;

FIG. 3 is a vertical section taken along the line 33 of FIG.- 2

FIG. 4 is a vertical section taken along the line 4-4 of P 1;

FIG. 5 is a vertical section taken along the line 55 of FIG. 1;; 7

FIG, 6 is a vertical section taken along the line 66 of FI 1;. l

7 FIG. 7 shows in its upper half a plan section taken along the line 7B-7B of FIG. 2 and in its lower half a plan section taken along the line '7A7A of FIG. 2; and FIG. 8 is a plan section taken along the line 88 of FIG. 2.

In the drawings the invention has been illustrated as embodied in a shop-assembled bottom-supported natural circulation steam generating unit designed on oil, natural gas or combination firing for a maximum continuous steam output of 150,000 pounds of steam per hour at a pressure of 435 psi. and a total temperature of 750 F. at the superheater outlet based on feedwater being supplied at a temperature of 330 F. The maximum cross section of the unit is fixed by shipping clearances. Preassembly of the components of the unit in the factory assures a better quality finished unit, minimizes the time and eifort required at the project site to place theunit in service, and assures optimum performance. The unit requires no prepared foundation other than a floor of sufficient strength, and no skilled labor for making the few connections required to place it in service.

The steam generating unit comprises a setting of rectangular cross-section having upright front and rear walls 10 and 11, respectively, uprightopposing side walls 12 and 13, an upper enclosing wall or roof 14 and a lower enclosing wall or floor 15. The space within the setting is divided by a pair of upright partition walls 16 into a furnace 1'7 and a pair of convection heating gas passes 19 symmetrically arranged at opposite sides of the setting and each having a gas outlet 20 at one end thereof and a gas inlet 21 at its opposite end opening to the rear end of the furnace 17. Each of the heating gas passes 19 extends along only a portion of the width of the setting and along almost the entire length of the furnace 17.

Each of the heating gas passes 26 is occupied by a bank of upwardly extending tubes 22 of relatively small diameter, preferably 2 inches outside diameter, disposed across the flow of gases and having their upper ends connected to an upper horizontally arranged steam and water drum 23 and their lower ends connected to a lower horizontally arranged water drum 24. The portions of the drums 23 and 24 in the heating gas passes 19 are protected from excessive heat by having the tubes 22 enter the drums over almost their entire exposed portions. The cross-flow of gases over the tubes 22 provides the most advantageous use of this convection heat absorbing surface and contributes to high steam generating capacity within the space available. Each tube 22 extends downwardly and outwardly from the drum 23, then vertically downward, and then downwardly and inwardly to the drum 24. The tubes 22 are arranged on alternate wide and narrow back spacing to simplify tube replacement; to provide an optimum quantity of heat absorption surface in the space available, thereby insuring high efficiency operation; and to minimize draft loss. The relatively small diameter of these tubes, together with the crossflow of gases thereover, provide optimum rates of heat transfer from the hot gases to the fluid in the tubes. The rapid flow of heat through the tubes to the small column of fluid in each tube makes the unit a notably fast steamer, capable of coming on the line quickly and rapidly responding to sudden load changes. Upper steam and water drum 23 is disposed superjacent and extends the entire length of the furnace 17 to a position substantially beyond the front wall thereof and has its longitudinal axis in the same vertical plane as the longitudinal centerline of the furnace 17. Lower water drum 24 extends the entire length of the furnace 1'7 and to a position slightly beyond the front wall 10 thereof and has its longitudinal axis in the same vertical plane as that of the upper drum 23.

Partition walls 16 extend upwardly from the lower drum 24, to the upper drum 23 and longitudinally of the setting from the front wall 19 to a location spaced from the rear wall 11 to provide the openings to the gas inlets 21 of the heating gas passes 19. Each partition wall is formed by closely spaced tubes 25 of relatively small outside diameter, preferably 2 inches, to promote high rates of heat transfer, having their intertube spaces closed by metallic studs welded to the tubes along the lengths thereof so that the wall is imperforate to gas flow, with the tubes 25 and the metallic studs associated therewith in the downstream half, with respect to gas flow, of the passes 19 being covered with refractory on the sides facing the heating gas passes 19. The large amount of water cooled surface in the partition walls 16 increases the effectiveness of the water cooled furnace without increasing its volume or its outside space requirements. Tubes 25 of the partition walls 16 are similar in form to the tubes 22; have their upper portions bent inwardly and upwardly at a slight angle to the horizontal for connection to the drum. 23 and to form with the metallic studs and refractory therebetween the roof of the furnace 17; and have their lower portions bent inwardly and downwardly at a slight angle to the horizontal for connection to the drum 24 and to form with the metallic studs and refractory therebetween the floor of the furnace 17, the latter being covered with a course of firebrick 27. Drums 23 and 24 are protected from excessive furnace heat by having the tubes'25 connected thereto enter the drums immediately adjacent to and on opposite sides of the vertical axes thereof and by covering the remaining exposed portions with refractory.

The rear wall 11, side walls 12 and 13, roof 14, and floor of the setting are formed by insulation covered gas-tight metallic casing lined by fluid cooled tubes secured thereto of relatively small outside diameter, preferably 2 inches to promote high rates of heat transfer.

Rear wall 11 includes a row of closely spaced tubes 2-? having their intertube spaces closed by refractory covered metallic studs secured to the tubes and their opposite ends connected to the drums 23 and 24. Each side wall includes a row of tubes 29 located in the corresponding heating gas pass 19, with the side wall tubes at the low temperature end of the corresponding heating gas pass 19 being relatively widely spaced to provide openings for the discharge of heating gases from the corresponding outlet 20, while the remaining side wall tubes are closely spaced and have their intertuhe spaces closed by refractory covered metallic studs welded thereto. Tubes 29 of the side walls have their upper portions bent inwardly and upwardly in converging relation for connection to the drum 23 and to form the roof 14- of the setting; and have their lower portions bent inwardly and downwardly to form the floor 15 of the setting. Front wall 10 comprises a row of upwardly extending tubes 3t) having their opposite ends connected to the drums 23 and 24. Some of the tubes 30 are disposed in the convection heating gas passes 19 and are covered with metallic casing, while the remaining tubes 30 are located in the furnace 17 and have their intertube spaces closed by refractory covered metallic studs welded to the tubes. Intermediate portions of some of the tubes 30 are suitably bent to form a circular opening 31 for the introduction of heating gases.

The rear or gas discharge end of the furnace 17 and the gas inlets 21 of the heating gas passes are occupied by a drainable type superheater 32. The superheater tube portions located at the inlet ends of the heating gas passes 19 absorb heat chiefly by convection and the tube portions located in the gas discharge end of the furnace absorb heat mostly by direct radiation from the furnace. The combination of the falling steam temperature characteristic of the radiant portion of the superheater with increasing steam flow, together with the rising steam temperature characteristic of the convection portion of the superheater with increasing steam flow, provides a substantially constant steam temperature over a relatively wide range of loads. Superheater 32 comprises two groups of horizontally disposed nested multi-looped tubes extending substantially the width of the setting and arranged in lat erally spaced vertically extending panels, with corresponding panels serially connected to define parallel flow paths for fluid flow between horizontally arranged upper inlet and lower outlet headers 33 and 34, respectively. Header 33 is connected to the drum 23 by tubes 35. The portions of the drums 23 and 24 in the superheater zone are protected from excessive heat by refractory 37. The superheater tubes are supported by lugs 38 welded to upright fluid cooled support tubes 39 at vertically spaced positions therealong, while the vertical spacing between tubes is maintained by lugs 40. Support tubes 39 have their opposite ends connected to the drums 23 and 24, are symmetrically arranged on opposite sides of the longitudinal centerline of the setting, and are positioned between the tubular panels. Lugs 38 and 40 cooperate to restrain lateral and vertical movements of the tubes while permitting longitudinal movement thereof. Lateral movement of the tubes is also restrainned by lugs 41, welded to the side wall tubes 29 at vertically spaced positions therealong and disposed "between the outermost loops of the tubular panels. Superheater 32 is partially screened against the high temperature heating gases passing thereto by two rows of widely spaced staggered tubes 42 disposed adjacent and upstream gas-wise of the superheater and extending between the drums 23 andld.

The steam generating unit is bottom supported by structural steel members including i-beams 43 adapted to be carried by the concrete foundation. Beams 43 extend the length of the setting and are symmetrically arranged on opposite sides of the centerline thereof. The weight of the drums 23 and 2d and of the tube extending therebetween is supported by longitudinally spaced I-beams 44 extending between the beams 43 and below thedrurn 2 and expansibly secured to castings 45 welded to the drum 24; and by an I -beam 46 extending between the beams 43 and fixedly secured to a casting 47 welded to the front end of the drum 24. Superheater outlet header 34 is carried by castings 48 projecting from one of the beams 43;

In accordance with the invention, the furnace 17 is supplied with heating gases by a horizontally extending cyclone type furnace 50 disposed adjacent to the front Wall of the furnace l7 and having its long'tudinal or major axis in the same vertical plane as the longitudinal center-lines of the furnace 17 and drums 23 and 24. Cyclone furnace is situated between the drums 23 and 24 and directly beneath the upper drum 23, with the lower drum 24 extending to a position slightly beyond the rear end of the cyclone furnace and the upper drum extending to a location beyond the front end of the cyclone furnace. While the cyclone furnace construction illustrated and hereinafter described is specifically designed and particularly adapted for firing by oil alone or in combination with natural gas, it 'will be understood that the cyclone furnace illustrated may also be adapted for firing by various kinds of liquid and gaseous fuels. The cyclone furnace comprises a horizontally elongated cylindrical combustion chamber 51, the circumferential boundary wall being formed by oppositely curved rows of tubes 52 having their intertube spaces closed, except in the zones of secondary air admission, as hereinafter described, by refractory covered metallic studs welded to the tubes, their upper ends connected to the overlying portion of drum 23-, and their lower ends connected to horizontal headers 53 disposed on opposite sides of the longitudinal centerline of and subjacent combustion chamber 51. Headers 53 are carried by castings 54 projecting from the beams 43 and are connected for fluid supply from the drum 24 by tubes 55 and from the drum 23 by upwardly extending tubes 56 symmetrically arranged on opposite sides of the vertical axis of the drum 23 and extending along the front end of and adjacent to the cyclone furnace.

The front or outer end of the combustion chamber 51 is formed by a circular wall 57 including upwardly extending tubes 58 symmetrically arranged on opposite sides of the vertical axis of the combustion chamber and having their intertube spaces closed by refractory covered metallic studs welded to the tubes, with intermediate portions of the tubes 58 being suitably bent to form a circular fuel inlet port 60. Tubes 58 have their upper ends connected to the drum 23, with the tubes on either side of the vertical axis of the combustion chamber having their lower ends connected to the header 53 on the corresponding side of the axis. The rear or inner end of the combustion chamber is partially closed by a circular wall 61 including upwardly extending tubes 62 having their intertub'e spaces closed by refractory covered metallic studs welded to the tubes and extending between the drum 23 and the headers 53 in substantially the same manner as the tubes 58, with intermediate portions of these tubes being suitably bent to form a circular gas outlet 63. Gas outlet 63 is connected to the gas inlet 31 of the furnace 17 by a cylindrical throat section 64 concentric with the combustion chamber 51 and formed by refractory material supported by metallic studs Welded to the portions of the tubes forming gas outlet 63 and gas inlet 31. The diameters of the gas outlet 63, gas inlet 31 and throat 64 are approximately the same, while the combustion chamber 51 has a diameter about the same as the width of the furnace 17 and the throat 64 has a diameter about three quarters of that of combustion chamber 51.

7 Fuel and air supply provisions for the cyclone furnace comprise metallic casing 65 suitably connected to the front wall 10 and surrounding and spaced from the cyclone furnace to form a windbox 66 to which combustion air is supplied by a pair of ducts 67 opening to the top of the windbo'x and connected to a forced draft fan, not shown. Casing 65 is formed with an aperture 68 closed by a circular cover plate 69 through which extends a pair of hollow horizontal distance pieces 71v each adapted to support the barrel of a liquid fuel burner 72. Each fuel burner barrel is provided with a fuel supply assembly 73 on its outer end and an atomizer head 74 On its inner end constructed and arranged to produce a coni cal spray of atomized fuel, with the barrel being of such a length that its discharge tip is slightly beyond the port 66 and within the combustion chamber 51 so that impin'gement of the liquid fuel on the wall 57 is avoided.

A frusto-conical air register 75 for the supply of primary and tertiary air to the burners is disposed in the windbox 66, surrounds the fuel burner barrels and is connected to the wall 57. Register 75 has its large outlet end 75A concentrically opening to and registering with the port on, its small tertiary air inlet end 75B opening to the Windbox 66 and slightly spaced from the cover 69 to provide a relatively restricted flow path to the inlet 75B and its circular boundary wall formed with a series of circumferentially spaced tangentially arranged primary air inlets 75C extending longitudinally of the register and arranged to impart a whirling motion to the entering primary air.

Secondary air is supplied to the combustion chamber 51 by circumferentially spaced ducts 76 of rectangular cross-section extending along substantially the entire length of the combustion chamber 51 and having their inlet ends opening to the win'db'ox 66 and their discharge ends opening tangentially in the same angular direction into the combustion chamber 51 by way of circumferentially extending axially spaced slot-like inlets 77 formed between the wall tubes 52. Each of the ducts 76 is occupied by a plurality of tubular gas burners 79 disposed at spaced positions along the length of the duct and connected to a branch manifold 80, with each pair of manifolds 86 on each side of the vertical axis of the combustion chamber being connected to a common gas supply manifold 81. Burners 79 of each duct 76 have their discharge ends located in corresponding inlets 77 of the corresponding duct and provided with suitable nozzles for the dispersion of the gas and are arranged so that the gas discharged therefrom enters the combustion chamber 51 with the combustion air of the corresponding duct 76 substantially tangentially to the circumferential wall of the combustion chamber.

Windbox 6'6 is partitioned by metallic plates 82 which cooperate with metallic casing '65, front wall 10, boundary walls of the combustion chamber 51, and the throat member 64 to form a by-pas's air flow passage 83. Passage 83 is supplied with combustion air by conduits 84 opening to the Windbox 66 and controlled by dampers 85 and each'arran'ged to direct a regulable quantity of the air supplied to the windbox radially into the whirling burning gases discharging from the outlet 63 by means of a series 'of 'circu'mfere-ntially and uniformly spaced ports 86 formed in the throat member '64.

In the operation of the vapor generator described, preheated air is supplied 'to the windbox by the ducts 67 at a high positive pressure and split into four streams, the major portion of the combustion air at all loads being used as secondary air and the remaining air being used as register air and by-pass air, with the percentage of by-pas's air, as controlled by dampers '8'5, increasing with increasing load and reaching a maximum at full load of about 30% of the total air flow and the percentages of register air and secondary air decreasing with increasing load, and with the portion of airdirected to the register '75 dividing about equally between the tertiary and ,primary air inlets thereof. The total air supplied to the cyclone furnace preferably ranges between 90 and of the theoretical combustion air requirements. Primary air enters the inlets 75C of the register 75 and whirls therethrough in ahigh velocity. stream in a counter-clockwise direction to the combustion "chamber 51; while tertiary air enters the inlet 75B and passes axially through the register generally inwardly and axially of the whirl-' a ing stream of primary air. Atomized fuel entering the combustion chamber 51 moves in a rapidly diverging conical path at a high velocity toward. the circumferential wall of the combustion chamber while mixing with the tertiary and primary air streams. The streams of 'high velocity secondary air and natural gas, when employed in combination with the firing of liquid fuel, discharging from the ducts '76 and burners 7?, respectively, tangentially enter the combustion chamber 51 in the same direction of rotation as and at the outer side of the whirling stream of primary air. The secondary air streams not only provide most of the air required for combustion but also protect the boundary walls of the combustion chamber from localized flame action, thereby preventing overheating or cutting of the tubes of the boundary walls. With the air streams and fuel entering the combustion chamber as described combustion of the fuel will progress at a rapid rate, which increases in the zone of secondary air admission, with a gradual mixing of the secondary air streams and natural gas streams with the enclosed streams of primary air and liquid fuel. The high velocity of the burning fuel and air mixtures causes the combustion gas stream to follow a helical path toward the rear of the combustionchamber where the gas is caused to discharge through the outlet 63 into the furnace 17 by way of the throat member 64. By-pass air enters the ports 86 and mixes with the gases discharging from the outlet 63. The use of by-pass air in increasing quantities with increase in load permits marked reduction of the air and gas pressure drop in the combustion chamber at high loads, thereby providing a considerable saving in forced draft fan cost and power, and minimizes combustion chamber pulsations to the end of providing smooth and stable combustion chamber operation at all loads; while providing the necessary additional air required to complete combustion of the fuel before the combustion gases enter the convection heating surfaces of the vapor generator. Heating gases entering the furnace 1'7 flow horizontally and rearwardly therethrough and over the screen tubes 42 and'the radiant heat absorbing portions of the superheater 32, then divide into parallel streams which flow reversely and horizontally through the heating gas passes 19 and successively over the convection heat absorbing tube portions of the sup'erheater 32; and the tube banks 22 disposed therein. The parallel streams then pass through the gas outlets 2%? to corresponding flues 37 which discharge to a common flue, not shown, for flow to another heat trap, if desired, or to the stack.

With the boiler construction described, feedwater enters the drum 23 and flows downwardly in parallel through the upright support tubes 56, the last few side wall tubes 29 and the front wall tubes 3% in the low temperature end of the heating gas passes 19, and the tubes of the last few rows, with respect to gas flow, of the tube banks 22. The downcomer tubes 22, 29, 38 are connected for parallel flow of fluid to the remaining tubes of the tube banks 22 and to the riser tubes of all the boundary walls of the furnace 17, heating gas passes 19, and combustion chamber 51; while tubes 56 supply additional' fiuid to the boundary wall tubes of the combustion chamber 51; Steam and water mixtures generated in riser tubes of the tube banks 22, and the boundary wall tubes of the furnace 17, heating gas passes 19 and combustion chamber 51, discharge to the drum 23 Saturated steam is supplied from the drum 23 to the superheater inlet header 33 byway of the tubes 35, the steam then passing through the tubesof the superheater and the outlet header 34 to the point of use.

- We claim:

r 1. A steam generator comprising:

(a) walls forming a setting;

(12) partition means dividing said setting into a heat-;

ing gas pass and a furnace adjoining and opening to one end of said heating gas pass;

() Walls including steam generating tubes forming a combustion chamber of circular cross section opening to said furnace;

(d) an upper steam and water drum extending longitudinally of and overlying said combustion chamber and furnace and having an end portion disposed adjacent to and projecting directly over said combustion chamber;

(2) a lower water drum;

(f) a bank of steam generating tubes in said heating gas pass extending between and connected to said drums;

(g) means connecting said combustion chamber wall tubes to said lower drum and to said end portion of the upper steam and water drum; and

(h) means firing said combustion chamber and effecting a flow of heating gases successively through said combustion chamber, said furnace chamber and said heating gas pass. a

2. A steam generator comprising:

(0) Walls including steam generating tubes forming a setting;

(b) partition means including steam generating tubes dividing said setting into a heating gas pass and a furnace adjoining and opening at one end to said heating gas pass;

(0) walls including steam generating tubes forming a combustion chamber of circular cr0ss-section having a gas outlet opening to said furnace;

(d) means forming a throat projecting outwardly from the combustion chamber and formed with a port and connecting said gas outlet to the opposite end of said furnace;

(e) an upper steam and water drum extending longitudinally of and overlying said combustion chamber and furnace and having an end portion disposed adjacent to and projecting directly over said combustion chamber;

(1) a lower water drum;

(g) a bank of steam generating tubes in said heating gas pass extending between and connected to said drums;

(It) means connecting said combustion chamber wall tubes to said lower drum and to said end portion of the upper steam and water drum; and

(i) means generating heating gases in said combustion chamber and effecting a flow of heating gases successively through said combustion chamber, said furnace chamber and said heating gas pass, said last named means including (1) means for supplying air to said port for mixing with the heating gases discharging from the combustion chamber gas outlet, and

(2) means for increasing the supply of air to said port as the steam generator load increases.

3. A steam generator comprising:

(a) walls forming a setting;

(1)) partition means dividing said setting into a heating gas pass and a furnace adjoining and opening at one end to said heating gas pass;

(c) walls including steam generating tubes forming a combustion chamber of circular cross-section having a gas outlet at one end and a fuel inlet port at its opposite end; V

(d) means forming a throat projecting outwardly from the combustion chamber and formed with a port and connecting said gas outlet to the opposite end of said furnace;

(e) an upper steam and water drum extending longitudinally of and overlying said combustion chamber and furnace and having an end portion disposed adjacent to and projecting directly over said combustion chamber;

(f) a lower water drum extending longitudinally of and underlying said furnace; V

(g) abanlcof steam generating tubes in said heating 9 gas pass extending between and connected to said drums;

(h) means connecting said combustion chamber wall tubes to said lower drum and to said end portion of the upper steam and water drum; and

(i means generating heating gases in said combustion chamber and effecting a whirling path of gas travel therein to and through said furnace and then through said heating gas pass, said last named means comprising (1) a burner in said fuel inlet port for supplying fluid fuel to said combustion chamber,

(2) means supplying air to said fuel inlet port,

(3) means for introducing a stream of air into said combustion chamber tangentially to the circumferential wall thereof at a location between the point of fuel entry and the gas outlet, and

(4) means for supplying air to said port of said throat member for mixing with the heating gases discharging from the combustion chamber gas outlet.

4. A shop-assembled steam generator comprising:

(a) walls forming a setting;

(b) partition means dividing said setting into a heating gas pass and a furnace adjoining and opening at one end to said heating gas pass;

() walls including steam generating tubes forming a combustion chamber of circular cross-section having a restricted circular gas outlet at one end and a circular fuel inlet port at its opposite end;

(d) means forming a throat projecting outwardly from the combustion chamber and formed with a port and connecting said gas outlet to the opposite end of said furnace;

(e) an upper steam and water drum disposed adjacent to extending longitudinally of and overlying said combustion chamber and furnace;

(f) a lower water drum extending longitudinally of and underlying said furnace;

g) a bank of steam generating tubes in said heating gas pass extending between and connected to said drums;

(h) means connecting said combustion chamber wall tubes to said drums; and

(1') means generating heating gases in said combustion chamber and effecting a whirling path of gas travel therein to and through said furnace and then reversely and in parallel through said heating gas passes, said last named means comprising (1) means forming a windbox surrounding said combustion chamber,

(2) means supplying air to said windbox,

(3) a burner in said fuel inlet port for supplying fluid fuel to said combustion chamber,

(4) means forming an air register of circular crosssection opening to said fuel inlet port and having its circular boundary wall formed with primary air inlets opening to said windbox and arranged to whirl streams of primary air through the register to said burner,

(5) a tangential secondary air inlet formed in the circular boundary wall of said combustion chamber and opening to said windbox,

(6) partition means in said windbox forming an air flow passage leading to the ports of said throat for passing a portion of the air supplied to said windbox through said port to the heating gases discharging from the combustion chamber gas outlet, and

(7) means for regulating the quantity of air supplied to the port of said throat member.

5 A steam generator comprising:

(a) walls including steam generating tubes forming a setting;

(b) partition means including steam generating tubes dividing said setting into a heating gas pass and a furnace laterally adjoining and opening at one end to said heating gas pass;

(0) walls including steam generating tubes forming a combustion chamber of circular cross-section having a restricted circular gas outlet at one end and a circular fuel inlet port at its opposite end;

(d) means forming a cylindrical throat project-ing outwardly from the combustion chamber and formed with a port and connecting said gas outlet to the opposite end of said furnace;

(e) an upper horizontal steam and Water drum disposed adjacent to extending longitudinally of and overlying said combustion chamber and furnace;

(j) a lower horizontal water drum extending longitudinally of and underlying said furnace;

(g) a bank of steam generating tubes in said heating gas pass extending between and connected to said drums;

([1) means connecting said combustion chamber wall tubes to said drums;

(i) means generating heating gases in said combustion chamber and effecting a whirling path of gas travel therein to and through said furnace and then reversely and in parallel through said heating gas passes, said last named means comprising (1) means forming a windbox surrounding said combustion chamber,

(2) means supplying air to said windbox,

(3) a burner in said fuel inlet port for supplying fluid fuel to said combustion chamber,

(4) means forming an air register of circular cross-section having an outlet at one end opening to said fuel inlet port and a tertiary air inlet at its opposite end opening to said windbox and having its circular boundary wall formed with circumferentially spaced tangential primary air inlets opening to said windbox and arranged to whirl streams of primary air through the register to said burner,

(5) a tangential secondary air inlet formed in the circular boundary Wall of said combustion chamber and opening to said windbox,

(6) partitions means in said windbox forming an air flow passage leading to the ports of said throat for passing a portion of the air supplied to said windbox through said port to the heating gases discharging from the combustion chamber gas outlet,

(7) means for regulating the quantity of air supplied to the port of said throat member.

6. A shop-assembled steam generator comprising:

(a) walls including steam generating tubes forming a setting;

(b) partition means including steam generating tubes dividing said setting into a heating gas pass extending the length of the setting and a furnace extending the length of the setting and laterally adjoining and opening at one end to said heating gas pass;

(0) Walls including steam generating tubes forming a combustion chamber having a restricted circular gas outlet at one end and a circular fuel inlet at its opposite end;

(d) means forming a cylindrical throat projecting outwardly from the combustion chamber and formed with circumferentially spaced ports and connecting said gas outlet to the opposite end of said furnace;

(e) an upper horizontal steam and water drum disposed adjacent to extending longitudinally of and overlying said combustion chamber and furnace;

(f) a lowerhorizontal water drum extending longitudinally of and underlying said furnace and having its longitudinal axis in the Same Vertical plane as the longitudinal axis of the upper drum;

(g) a bank of steam generating tubes in said heating gas pass extending between and connected to said drum;

(It) means connecting said combustion chamber Wall tubes to said drums; and

(i) means generating heating gases in said combustion chamber and effecting a whirling path of gas travel therein to and through said furnace and then reversely through said heating gas pass, said last named means comprising (1) means forming a windbox surrounding said combustion chamber,

(2) means supplying air to said windbox,

(3) a burner in said fuel inlet port for supplying fluid fuel to said combustion chamber,

(4) means forming an air register of circular cross-section having an outlet at one end opening to said fuel inlet port and a tertiary air inlet at its opposite end opening to said windbox and having its circular boundary wall formed with circumferentially spaced tangential primary air inlets opening to said windbox and arranged to whirl streams of primary air through the register to said burner,

(5) a multiplicity of circumferentially spaced axially extending tangential secondary air inlets formed in the circular boundary wall of said combustion chamber and opening to said windbox,

(6) partition means in said windbox forming an air flow passage leading to the ports of said throat for passing a portion of the air supplied to said windbox through said ports to the heating gases discharging from the combustion chamber gas outlet, and

(7) means for regulating the quantity of air supplied to the port of said throat member.

7. A steam generator comprising:

(:1) Walls forming a setting;

(b) partition means dividing said setting into a pair of heating gas passes extending the length of the setting and a furnace extending the length of the setting and disposed intermediate and opening at one end to each of said heating gas passes;

(c) Walls including steam generating tubes forming a combustion chamber of circular cross-section having a restricted gas outlet at one end and a fuel inlet at its opposite end;

(d) means forming a throat projecting outwardly from the combustion chamber and formed with circumferentially spaced ports and connecting said gas outlet to the opposite end of said furnace;

(e) an upper horizontal steam and Water drum disposed adjacent to extending longitudinally of and overlying said combustion chamber and furnace;

(f) a lower horizontal water drum extending longtudinally of and underlying said furnace;

(g) a bank of steam generating tubes in each of said heating gas passes extending between and connected to said drums;

(It) means connecting said combustion chamber wall tubes to said drums; and (i) means generating heating gases in said combustion chamber and effecting a whirling path of gas travel therein to and through said furnace and then reversely and in parallel through said heating gas passes, said last named means comprising (1) means forming a. windbox surrounding said combustion chamber, (2) means supplying air to said windbox, (3) a burner in said fuel inlet port for supplying fluid fuel to said combustion chamber, (4) means forming an air register of circular cross-section having an outlet at one end opening to said fuel inlet port and a tertiary air inlet i 2 at its opposite end opening to said windbox and having its circular boundary Wall formed with circumferentially spaced tangential primary air inlets opening to said windbox and arranged to whirl streams of primary air through the register to said burner,

(5) a multiplicity of circumferentially spaced axially extending tangential secondary air inlets formed in the circular boundary Wall of said combustion chamber and opening to said Windbox,

(6) partition means in said windbox forming an air flow passage leading to the ports of said throat for passing a portion of the air supplied to said windbox through said ports to the heating gases discharging from the combuston chamber gas outlet, and t a (7) means for regulating the quantity of air supplied to the ports of said throat member.

8. A steam generator comprising:

(a) Walls including steam generating tubes forming a setting;

(b) partition means including steam generating tubes dividing said setting into a pair of heating gas passes extending the length of the setting and a furnace extending the length of the setting and disposed intermediate and opening at one end to each of said heating gas passes;

(0) Walls including steam generating tubes forming a cylindrical combustion chamber having a restricted circular gas outlet at one end and a circular fuel inlet at its opposite end;

(:5) means forming a cylindrical throat projecting outwardly from the combustion chamber and formed with circumferentially spaced ports and connecting said gas outlet to the opposite end of said furnace;

(e) an upper horizontal steam and water drum extending longitudinally of and overlying said combustion chamber and furnace and having an end portion disposed adjacent to and projecting directly over said combustion chamber;

(7) a lower horizontal water drum extending longitudinally of and underlying said furnace and having its longitudinal axis in the same vertical plane as the longitudinal axis of the upper drum;

(g) a bank of steam generating tubes in each of said heating gas passes extending between and connected to said drums;

(It) means connecting said combustion chamber Wall tubes to said lower drum and to said end portion of the upper steam and Water drum; and

(i) means generating heating gases in said combustion chamber and effecting a whirling path of gas travel therein to and through said furnace and then reversely and in parallel through said heating gas passes, said last named means comprising (1) means forming a windbox surrounding said combustion chamber,

(2) means supplying air to said windbox,

(3) a burner in said fuel inlet port for supplying fluid fuel to said combustion chamber,

(4) means forming an air register of circular crosssection having an outlet at one end opening to said fuel inlet port and a tertiary air inlet at its opposite end opening to said windbox and having its circular boundary wall formed with circumferentially spaced tangential primary air inlets opening to said windbox and arranged to whirl streams of primary air through the register to said burner,

(5) a multiplicity of circumferentially spaced axially extending tangential secondary air inlets formed in the circular boundary wall of said combustion chamber and opening to said windbox,

(6) partition means in said windbox forming an air flow passage leading to the ports of said throat for passing a portion of the air supplied to said Windbox through said ports to the heating gases discharging from the combustion cham ber gas outlet, and

(7) means for regulating the quantity of air supplied to the ports of said throat member.

References Cited in the file of this patent UNITED STATES PATENTS Jerie et a1 Nov. 25, 1958 Hamilton et a1 Feb. 27, 1962 Aref June 19, 1962 FOREIGN PATENTS Great Britain Mar. 30, 1955 France July 13, 1955 

1. A STEAM GENERATOR COMPRISING: (A) WALLS FORMING A SETTING; (B) PARTITION MEANS DIVIDING SAID SETTING INTO A HEATING GAS PASS AND A FURNACE ADJOINING AND OPENING TO ONE END OF SAID HEATING GAS PASS; (C) WALL INCLUDING STEAM GENERATING TUBES FORMING A COMBUSTION CHAMBER OF CIRCULAR CROSS-SECTION OPENING TO SAID FURNACE; (D) AN UPPER STEAM AND WATER DRUM EXTENDING LONGITUDINALLY OF AND OVERLYING SAID COMBUSTION CHAMBER AND FURNACE AND HAVING AN END PORTION DISPOSED ADJACENT TO AND PROJECTING DIRECTLY OVER SAID COMBUSTION CHAMBER; (E) A LOWER WATER DRUM; (F) A BANK OF STEAM GENERATING TUBES IN SAID HEATING GAS PASS EXTENDING BETWEEN AND CONNECTED TO SAID DRUMS; (G) MEANS CONNECTING SAID COMBUSTION CHAMBER WALL TUBES TO SAID LOWER DRUM AND TO SAID END PORTION OF THE UPPER STEAM AND WATER DRUM; AND (H) MEANS FIRING SAID COMBUSTION CHAMBER AND EFFECTING A FLOW OF HEATING GASES SUCCESSIVELY THROUGH SAID COMBUSTION CHAMBER, SAID FURNACE CHAMBER AND SAID HEATING GAS PASS. 